Potential bug in Shape Context

edit

I have found the reason. It comes from the reference Matlab implementation, the comments explain it:

   % compute shape contexts for (transformed) model
   [BH1,mean_dist_1]=sc_compute(Xk',zeros(1,nsamp1),mean_dist_global,nbins_theta,nbins_r,r_inner,r_outer,out_vec_1);

   % compute shape contexts for target, using the scale estimate from
   % the warped model
   % Note: this is necessary only because out_vec_2 can change on each
   % iteration, which affects the shape contexts.  Otherwise, Y does
   % not change.
   [BH2,mean_dist_2]=sc_compute(Y',zeros(1,nsamp2),mean_dist_1,nbins_theta,nbins_r,r_inner,r_outer,out_vec_2);